In today's radio communications networks a number of different technologies are used, such as Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible technologies for radio communication. A radio communications network comprises radio base stations providing radio coverage over at least one respective geographical area forming a cell. The cell definition may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. User equipments (UE) are served in the cells by the respective radio base station and are communicating with respective radio base station. The user equipments transmit data over an air or radio interface to the radio base stations in uplink (UL) transmissions and the radio base stations transmit data over an air or radio interface to the user equipments in downlink (DL) transmissions.
New releases of the specifications for the technologies above are continuously being developed within frameworks, such as, e.g. the 3rd Generation Partnership Project (3GPP).
For example, in the period from Release 8 to Release 10 of the 3GPP/WCDMA specification, the support of multi-cell downlink transmissions for High-Speed Downlink Packet Access (HSDPA) where introduced. Further, according to one example, in Release 8 of the 3GPP/WCDMA specification, a Dual-Cell HSDPA (DC-HSDPA) operation was standardized. This allows the radio communications network to schedule simultaneous DL transmissions on two adjacent downlink carriers to a UE simultaneously. An adjacent downlink carrier, frequency or cell may be described as a carrier, frequency or cell whose center is within 5 MHz of the center of the currently used frequency and belongs to the same frequency band as that of the currently used frequency. Note that the terms “carrier”, “frequency” and “cells” are used interchangeably herein.
According to another example, in Release 9 of the 3GPP/WCDMA specification, support for DC-HSDPA in combination with Multiple Input Multiple Output (MIMO) transmissions was introduced. This provided for peak downlink data rates of up to 84 Mbps. In this release, support for a Dual-Band DC-HSDPA operation was also introduced. This extended the DC-HSDPA operation of Release 8 such that the two configured downlink carriers could be located in different frequency bands.
According to a further example, in Release 10 of the 3GPP/WCDMA specification, a 4 Carrier High-Speed Downlink Packet Access (4C-HSDPA) operation was introduced. This provided for peak downlink data rates of up to 168 Mbps. The four (4) configured downlink carriers may be spread across at most two frequency bands. However, all configured downlink carriers within one and the same frequency band must be adjacent in this 4C-HSDPA operation according to the Release 10 of the 3GPP/WCDMA specification; that is, the configured downlink carriers must be adjacent with in one frequency band or spread across two frequency bands in an adjacent manner.
However, it has been noted that many operators operating within the radio communication network do not have carriers, frequencies or cells allocated contiguously in a frequency band, that is, located adjacent to each other. For example, one operator may have two contiguous carriers in one part of the frequency band and two contiguous carriers in another part of the frequency band. In between the two pairs of contiguous carriers in the frequency band, another operator may have and utilize one or more carriers.
This means that operators that do not have strictly contiguous carriers in the frequency band may be prevented from realizing the potential of using, e.g. the 4C-HSDPA operation in Release 10 of the 3GPP/WCDMA specification in the radio communication network.